1. Field of the Invention
The invention relates to feed-through devices or shortly named ‘feed-throughs’ that are capable of bearing a mechanical load and are therefore fault-proof, and also to the use thereof. In particular, the invention relates to electrical and/or optical feed-throughs, by means of which signals and/or electrical currents can be guided from or into security-relevant containers. In particular, this also includes feed-throughs in the low-voltage and medium-high voltage range. Reference is made generically here to large-scale feed-throughs, since their components may have diameters from a few centimeters to many centimeters and the overall weight may be several kilograms.
2. Description of Related Art
In the case of containers for storing or conveying flammable hazardous material, containers of energy production devices or storage devices, or in the case of containers in which hazardous materials are produced and/or stored, referred to collectively as containment structures, it is often necessary to introduce and/or remove electrical currents and/or signals of measurement devices, sensors and/or actuators into/from the container. For example, in facilities for conducting and/or conveying liquefied natural gas, submersible pumps arranged in the container interior are used. In order to introduce the power necessary for the pumps into the container interior, connection devices comprising sealing electrical feed-throughs are used. In the case of energy production units, for example steam generators of power plants, the energy produced has to be removed safely and/or apparatuses in these energy production units have to be supplied with power. To this end, a feed-through is typically flange-mounted to a flange of the containment structure, for example a pressure vessel.
In particular in the case of pressure vessels containing flammable gases and/or liquids, it is important here that the feed-through remains tight over a long period of time. Particularly when storing flammable substances, which may form explosive gas mixtures, there is still the risk that, even with the smallest of leaks which are not critical per se, gas mixtures can be formed in sealed regions of the feed-through. For example, such regions can be formed in fitted protective housings. Should this then lead to an explosion, the feed-through may be damaged in such a way that the hazardous material then exits quickly from the container that is to be closed. This is also relevant in particular in facilities for producing nuclear power, in particular in order to ensure safe containment of the reactor housing, even in the event of a fault.
EP 2 031 288 B1 describes an electrical feed-through for liquid containers, in which an electrical conductor is soldered in a flange by means of an insulating feed-through sleeve. The flange has a feed-through opening, in which the electrically insulating feed-through sleeve is soldered directly. The insulating feed-through sleeve is tubular and in its interior has an electrical conductor which has a diameter smaller than the inner diameter of the feed-through sleeve. At its ends, the gap between the feed-through sleeve and conductor is hermetically closed, such that a relatively large hollow space is located between the feed-through sleeve and the conductor. A bore is located in the feed-through sleeve. The flange is formed in two parts, such that a hollow space is located between the flanges and, through the bore in the feed-through sleeve, connects the hollow space in the feed-through sleeve to the hollow space between the flanges, or a one-part flange is provided with a bore that corresponds to the bore in the feed-through sleeve. By monitoring the pressure in the hollow space of the feed-through sleeve, gas penetrating into the feed-through sleeve can be detected and damage to the feed-through can thus be monitored.
This feed-through is afflicted by the problem that the electrically insulating feed-through sleeve has a specific length. It is tubular and has a hollow space which extends around the inner conductor. The material of the feed-through sleeve is a ceramic, which is known to be a brittle material. In the case of such a feed-through unit, the feed-through sleeve specifically may break under mechanical load. The barrier between the containment structure and the surrounding environment would then be broken. Therefore the feed-through shown in this reference cannot be considered to be fault-proof. Aside from this, the production of such a feed-through sleeve is associated with a high manufacturing outlay.